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DOI:
https://doi.org/10.57187/5135

Original article

Vol. 156 No. 7 (2026)

Severe acidaemia in the emergency department: a retrospective cohort study

Cite this as:
Swiss Med Wkly. 2026;156:5135
Published
23.07.2026

Summary

OBJECTIVES: Analysis of acid-base status is crucial for diagnosing and treating underlying disorders. There is a scarcity of data on causes of severe acidosis in emergency patients. The current analysis aimed to evaluate the cause of severe acidaemia on admission to an emergency department by using the physical-chemical approach as simplified by Story. Moreover, we evaluated the outcome of patients with severe acidaemia on admission to the emergency department in terms of hospitalisation, length of hospital stay, ICU admission and in-hospital mortality.

METHODS: The retrospective analysis included all adult patients presenting to the Emergency Department of Kepler University Hospital Linz, Austria, with a pH <7.15 in venous blood gas between 1 July 2022 and 30 June 2024. Respiratory acidosis was defined as pCO2 >45 mm Hg, while respiratory alkalosis was defined as pCO2 <35 mm Hg. Analysis of metabolic components was performed using Story’s simplified approach.

RESULTS: The study included 79 patients with severe acidaemia (pH <7.15). Median pH was 7.08 (interquartile range [IQR]: 7.04–7.11) with a minimum of 6.78. The pCO2 was 41 mm Hg / 5.47 kPa (IQR: 33–78 mm Hg / 4.4–10.4 kPa) with a minimum of 13/1.73 and a maximum of 164/21.86. Median standard bicarbonate was 11 mmol/l (IQR: 8–17) with a minimum of 3.9. Median base excess was –16.3 mmol/l (IQR: –21.85 – –5.75) with a minimum of –29.7. Median lactate was 3.6 mmol/l (IQR: 1.8–8.8). Primary respiratory acidosis was present in 49% of patients, while 51% had primary metabolic acidosis. 58% of patients with primary metabolic acidosis had a combination of strong ion difference-associated and unmeasured-anion (UMA) acidosis. The main causes of UMA acidosis were lactic acidosis, diabetic ketoacidosis and uraemia.

CONCLUSION: Severe acidaemia is caused equally by primary respiratory and metabolic acidoses. Combinations of different mechanisms leading to severe acidaemia are common and can potentially mask therapeutically relevant acid-base disorders such as diabetic ketoacidosis.

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